TORONTO -- Kyle Drabek was forced to leave Wednesday afternoon's 6-2 loss to the Nationals in the fifth inning because of a right elbow injury.

Drabek felt a pop in the elbow while throwing his 85th pitch of the game, and he immediately called for trainer Hap Hudson and manager John Farrell.

The Toronto right-hander passed a series of tests in the clubhouse, but he will need to undergo further evaluations on Wednesday night before a timetable for his return can be established.

"I threw the ball and I kind of felt a little popping sensation in the back of my elbow," Drabek said. "I don't know how fast [the pitch] was, but I knew the velocity was down. Just for a precaution, [it was] probably smart to take me out."

142 wins

110 wins

Drabek previously underwent Tommy John surgery in 2007, but he said this incident felt much different. Toronto's No. 4 starter believes the ligament is fine, with the discomfort instead felt in the back of the elbow.

The 24-year-old becomes the second Blue Jays starting pitcher to go down in the past three days. Toronto lost No. 2 starter Brandon Morrow on Monday with a left oblique strain. Morrow is currently on the 15-day disabled list, and there is no timetable for his return.

The Blue Jays are attempting to remain optimistic that Drabek's injury won't be nearly as severe, but it's still too early to say with absolute certainty.

"He has been checked out in the training room, he has full strength, he has full stability, just based on the training room tests," Farrell said. "He has additional tests scheduled for later today, so to speculate further, we won't be able to do so until those results come back.

"Most encouragingly, he felt no discomfort in the training room afterwards, but when he felt the pop on the mound, it was clear we had to take him out for precautionary reasons."

Drabek was charged with four runs on seven hits while walking two and striking out one in 4 1/3 innings. He threw 51 of his 85 pitches for strikes but departed with his club trailing, 4-2.

The native of Texas is 4-7 with a 4.67 ERA in 13 starts this season. He also has walked 47 and struck out 47 in 61 1/3 innings.

"Not sure right now," Drabek said when asked if he would be able to make his next start. "It's just a little sore right now. See what George [Poulos, head trainer] has for me. Obviously I want to go back out and pitch, but it's up to the trainers and the coaches."